Method of estimating the injection pressure of an internal combustion engine

Abstract

A method of estimating an injection pressure for an internal combustion engine of an automotive system is disclosed that is well-suited for use with a digital pressure sensor, which periodically acquires injection pressure signals. An updated injection pressure value is calculated starting from an injection pressure signal and compensated with a pressure-correcting parameter, based on an elapsed time from the injection pressure signal acquisition, an actual engine speed and an actual fuel injection quantity.

The invention claimed is: 
     
       1. An internal combustion engine comprising a fuel injection system provided with a digital pressure sensor, the fuel injection system being operable to:
 periodically acquire an injection pressure signal from the digital pressure sensor; 
 calculate an updated injection pressure value, starting from the injection pressure signal; 
 compensate the updated injection pressure value with a pressure correcting parameter, based on an elapsed time from the injection pressure signal acquisition, an actual engine speed and an actual fuel injection quantity; and 
 control the fuel injection based on the compensated updated pressure value. 
 
     
     
       2. The internal combustion engine of  claim 1  comprising a computer program including non-transitory computer-code. 
     
     
       3. The internal combustion engine of  claim 2  comprising a memory on which the computer program is stored. 
     
     
       4. The internal combustion engine of  claim 2  comprising a control apparatus having an electronic control unit, a data carrier associated to the electronic control unit and the computer program. 
     
     
       5. A method of estimating an injection pressure for an internal combustion engine having a fuel injection system with a digital pressure sensor which periodically acquires injection pressure signals, the method comprising:
 calculating an updated injection pressure value, starting from an injection pressure signal; 
 compensating the updated injection pressure value with a pressure correcting parameter, based on an elapsed time from the injection pressure signal acquisition, an actual engine speed and an actual fuel injection quantity; and 
 controlling the fuel injection based on the compensated updated pressure value. 
 
     
     
       6. The method according to  claim 5 , wherein said elapsed time is calculated by setting an internal counter to zero, when an angular-based task is scheduled, incrementing said internal counter, until said angular-based task is called, and resetting said internal counter to zero when an injection pressure signal is acquired by the digital pressure sensor. 
     
     
       7. The method according to  claim 6 , further comprising calculating said pressure correcting parameter from a calibrated map whose input parameters are an actual engine speed, an actual fuel quantity and a value assumed by said internal counter, wherein said calculation takes place when said angular-based task is called. 
     
     
       8. The method according to  claim 6 , wherein said internal counter is a time-based counter. 
     
     
       9. The method according to  claim 5 , wherein said internal counter is an angular-based counter. 
     
     
       10. The method according to  claim 5 , wherein said pressure correcting parameter is an adding factor and said updated injection pressure value is calculated by algebraically summing said injection pressure signal and said adding factor. 
     
     
       11. The method according to  claim 5 , wherein said pressure correcting parameter is a multiplying factor and said updated injection pressure value is calculated by multiplying said injection pressure signal and said multiplying factor.